Coupling effect of operational factors on heat extraction from a coal pile using a two-phase closed thermosyphon

• Published in: Energy (Oxford) Vol. 239; p. 122371
• Main Authors: Xiao, Yang, Liu, Jing-Wen, Zeng, Jun-Feng, Lu, Xing, Tian, Yuan, Shu, Chi-Min
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 15.01.2022; Elsevier BV
• Subjects: Aspect ratio; Coal; Coal fire; Coupling; Coupling effect; Filling percentage; Heat transfer; Heat treatment; Liquid working medium; Numerical prediction; Spontaneous combustion; Thermosyphons; Variance analysis; Working fluids; Liquid working medium; Coal fire; Aspect ratio; Filling percentage; Coupling effect
• ISSN: 0360-5442; 1873-6785
• DOI: 10.1016/j.energy.2021.122371

Thermal extraction from a coal fire by using a two-phase closed thermosyphon (TPCT) is a clean and sustainable approach to govern coal spontaneous combustion (CSC). However, investigations into the elimination of coupling effects and the optimal design of the primary operational variables of TPCTs for effective prevention and control of coal fires are lacking. Through orthogonal experiments, this study examined the influence of the major factors of nanoliquid as liquid working medium, filling percentage, and aspect ratio on TPCT heat transfer. Analysis of variance (ANOVA) was performed to obtain the optimal combination of variables. The results indicated that when the coal temperature was 100 °C, the highest heat transfer performance of TPCTs among all experimental test cases was achieved which utilising CuO–H2O as the liquid working fluid, a 25% filling percentage, and an aspect ratio of 15. The optimal combination of variables obtained using ANOVA constituted a CuO–H2O liquid working medium, a filling percentage of 15%, and an aspect ratio of 15. Subsequent numerical predictions indicated a 74.9% increase in the heat transfer performance of TPCT with the aforementioned combination of ANOVA-based variables compared with the experimental combinations. [Display omitted] •Designed orthogonal experiments to explore the heat transfer of TPCTs.•Identified the best combination of variables through ANOVA.•Conducted numerical simulations of TPCTs based upon the experimental data and ANOVA.•Simulation of TPCT heat transfer based upon ANOVA outperformed that based upon experimental data.